Wet wells are the holding sump for gravity-flow sewer systems. As material enters the well and the water level rises, pumps are engaged and pump the sewage out to a forced main, or the sewage is lifted to a higher grade to continue the gravity flow to the outlet point. Solid material accumulates in the bottom of the wet well and incoming sewage lines.
Lift stations are low points in gravity-flow sewer systems where incoming sewage is pumped from a well to a higher grade so it can continue the gravity flow to a treatment plant. As solid material enters the lift station, buildup will occur on the bottom of the sump and inlet pipes, and pumps inside of the station. Solid material can often plug and damage pumps, so periodic cleaning is required to remove the material from the lift station to help prevent damage to components.